Electronic control circuit

ABSTRACT

An electronic control circuit for providing an output signal for missile firing or the like comprising a source of oscillating electrical energy, structure for storing a predetermined amount of electrical energy, an electrical reactance for transferring the oscillating electrical energy into the storage structure, means for limiting the electrical charge stored in the storage structure and for indicating the storage structure is charged, trigger structure for providing a controlled discharge of the stored energy to provide the output signal, and means for shutting off the source of alternating electrical energy during discharge of the storage means.

United States Patent 1151 3,639,826 Grundberg 1 1 Feb. 1, 1972 [54] T NICONTROL CIRCUIT 3,421,069 l/l969 Minks.... ..321/2 3,435,320 3/1969 Leeet al. ..32l/2 [72] Inventor: Kenneth Grundberg, 3012 Maplewood,

R y l Mich- 48073 Primary ExaminerWilliam H. Beha, Jr. [22] Filed, Mar12 1970 AttorneyWhittemore,Hulbert&Belknap [21] AppLNo; 18,010 [57]ABSTRACT Related Application Data An electronic control circuit forproviding an output signal for missile firing or the like comprising asource of oscillating Continuation-impart 0f electrical energy,structure for storing a predetermined 1968, abandoned. amount ofelectrical energy, an electrical rcaetance for trans ferring theoscillating electrical energy into the storage struc- [52] U.S.Cl..321/2,3l5/209CD,315/241, ture, means for limiting the electricalcharge stored in the 321/ 18 storage structure and for indicating thestorage structure is [5 l Int. Cl ..H02m 3/32, H05b charged, triggerstructure for providing a controlled discharge [58] Field of Search..321/2, 18; 331/1 12; f h stored n gy to pr i the output gn and m n315/209 CD, 241; 123 /148 E for shutting off the source of alternatingelectrical energy during discharge of the storage means. [56] ReferencesCited UN EPi ATE PHFlYIE 7 Claims 6 Drawing Figures mama] rm usrz3.839.826

SHEET 1 [IF 3 INVENTOR KENNETH GRUNDBERG M c 711.21%; BY

ATTORNEYS mzmanrza H972 sisaslaz SHEEY 3 0F 3 v INVENTOR KENNETH-/,GRUNDBERG ATTORNEYS ELECTRONIC CONTROL CIRCUIT CROSSREFERENCE TORELATED APPLICATIONS The present application is a continuation-in-partof patent application Ser. No. 701,384, filed Jan. 29, 1968, whichapplication is now abandoned.

BACKGROUND OF THE INVENTION 1. Field of the Invention The inventionrelates to means for and a method of providing electrical output signalswhich may be control signals or only regulated, converted or invertedsignals. More specifically the invention refers to a control circuit forand method of providing controlled electrical pulse output signals forengine ignition or missile firing or the like.

2. Description of the Prior Art In the past, circuit for providingelectrical pulse output signals for igniting turbine engines andregulated, converted or inverted output signals or the like have beendeficient in theefficiency with which energy has been developed, storedand/or dissipated through the load. Thus, electromagnetic andelectrohydraulic systems have been used in the past to provide energyfor or for transferring energy to a storage device and/or forsubsequently discharging the energy through a load with resultant lowefficiency in energy transformation.

In addition, in firing missiles such as grenades and the like, it isdesirable to have a means for and method of producing a pulse ofelectrical energy of positively known magnitude on command and to beassured at the time of command that the required energy is available.With prior control circuits, an electrical signal at a predeterminedvoltage level together with an indication of the correct voltage levelhas not been available in a reasonably compact, reliable, inexpensiveform.

SUMMARY OF THE INVENTION The invention therefore includes the provisionof a control circuit for and a method of providing electrical outputsignals for ignition of turbine engines or control of firing of missilesor the like which is simple, economical and efficient.

The control circuit of the invention includes an oscillator fordeveloping electrical nulses, means for storing the electrical pulsesand for periodically discharging the electrical pulses across a load atlow or high voltage. Optional means for regulating the oscillator may beincluded in the control circuit in accordance with the invention. In thecontrol circuit of the invention transformer means are provided fortransfer of electrical energy from the oscillator to the storage devicewhereby the transfer is particularly efficient.

In addition, the control circuit of the invention may include means formaintaining the signal on the storage means at a predetermined levelbefore discharge together with means for indicating the voltage", at thepredetermined level and for providing discharge from the storage meansonly on command. Also, the control circuit includes means for cuttingoff the oscillator during discharge of the storage means.

In one modification of the invention a circuit is disclosed forproviding a converted alternating to direct current, regulated orinverted output signal at a level either above or below the level of theinput signal at a theoretical 100 percent efiiciency over a wide rangeof supply voltages and loads.

The method of providing the electrical output signals in accordance withthe invention includes developing electrical oscillations, storing theelectrical energy derived from the oscillations and discharging thestored electrical energy through a load. The electrical energy may bedischarged through the load continuously at predetermined uniformintervals or only on command. As indicated above, the stored energy maybe indicated when the energy is to be discharged on command and themethod of providing electrical output signals may include the steps ofstopping the development of electrical oscillations during discharge ofthe storage device and charging or discharging the storage device inaccordance with the voltage level of the electrical energy storedtherein.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of anelectrical control circuit constructed in accordance with the inventionparticularly suited for engine ignition use.

FIG. 2 is a modification of the electrical control circuit of FIG. 1.

FIG. 3 is a modification of the electrical control circuit of FIG. 2. j

FIG. 4 is a schematic diagram of a second embodiment of the inventionparticularly suited for missile firing.

FIG. 5 isfa schematic diagram of another embodiment of the inventionparticularly suited for providing a regulated, converted or invertedoutput at a chosen signal level with high efficiency over a range ofinput signals and loads.

FIG. 6 is a modification of the circuit of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The electronic control circuit10 illustrated in FIG. 1 may be connected to a plurality of differentsources of electrical energy across the terminals 12 and 14 including,for example, a direct current source or alternating current sources ofvaried frequency of, for example, up to 30 volts and will produce anoutput pulse across the electrodes 16 and 18 of the airgap igniter 52 atrelatively low voltage and at a frequency determined by the magnitude ofthe input voltage, the frequency of the oscillator circuit 20, themagnitude of the capacitor storage device 22 and the breakdown voltageof the spark gap structure 24.

More specifically, the oscillator circuit 20 includes the transistor. 26having the base 28, emitter 30 and collector 32, as shown in FIG. 1. Thebase 28 of the oscillator semiconductor 26 is connected through asecondary portion 34 of the electrical reactance transformer 36 to acentral point of the voltage divider including the resistors 38 and 40connected across the electric terminals 12 and 14. The emitter 30 of thetransistor 26, as shown, is connected to the terminal 14, while thecollector of the transistor 26 is connected to the terminal 12 throughthe primary portion 42 of the transformer 36.

Additionally, the secondary portion 44 of the transformer 36 isconnected through the rectifying diode 46 and resistance 48, whileresistance is not necessary tothe operation of the circuit 10, to oneside of the capacitor storage device 22. The other side of the capacitorstorage device 22 is connected to the terminal 14.

A protecting resistor 50 is provided across the airgap igniter 52 whichincludes the resistance 54 in addition to the terminals 16and 18 toprovide a load for the circuit 10 with the airgap igniter removed. Theairgap igniter 52 may, for example, be a spark plug in which case theresistance 54 may not be a physicalresistor.

In overall operation of the electronic control circuit 10, when thecircuit 10 is connected across a source of electrical energy at theterminals 12 and 14, a voltage appears across the resistor 40 of thevoltage divider to provide a forward bias on the oscillator transistor26 to produce electrical oscillations. The oscillator transistor 26 willconduct through the primary portion 42 of the transformer 36 to induce asignal in the secondary portion 34 of the transformer 36 in oppositionto the bias applied to the base of transistor 26 due to the signalapplied across terminals 12 and 14. The induced signal will causethejtransistor 26 to stop conducting.

When the transistor 26 is cut off, the current through the primaryportion 42 of the transformer 36 ceases and the field therearoundcollapses to produce a signal in the secondary portion 44 of transformer36, a portion of which is transferred through the diode 46 andresistance 48 and is stored on the capacitor 22. The cycle of theoscillator circuit 20 is thus completed and will be repeated as long asthe source of electrical energy is connected to the terminals 12 and 14with additional energy being transferred to the capacitor 22 up to thelimit set by the spark gap structure 24.

After a number of cycles of the oscillator 26, the signal stored on thecapacitor 22, which it is pointed out is transferred to the capacitor 22from the oscillator 26 with a theoretical 100 percent efficiency due tothe transformer vided across the electrodes 16 and 18 of the airgapigniter will be relatively low with the control circuit 10. Provided ahigher voltage across the electrodes 16 and 18 of the igniter 52 isdesired, the circuit of FIG. 1 may be modified as illustrated in FIG. 2;

The circuit 56 of FIG. 2 is exactly the same as the circuit 10 of FIG.1, except for the inclusion therein of the discharge transformer 58 andadditional capacitor 60. In addition, the

resistor 54 of the airgap igniter is not shown since it is not essentialin the operation of either circuit 10 or56. The similar components incircuits 10 and 56 have been given the same reference characters.

In operation of the modified electronic control circuit 56, on breakdownof the spark gap 24, the capacitor 22 discharges through the primaryportion 62 of the transformer 58 into the capacitor 60, whereby anelectrical signal of increased voltage is provided across the electrodes16 and 18 through the secondary portion 64 of the transformer 58.

With both the'circuits l and 56 of FIGS. 1 and 2, the frequency of theoutput signal across the electrodes 16 and 18 will vary with themagnitude of the input electrical signal across the terminals 12 and 14with the rest of the circuit constants identical. The modifiedelectronic control circuit 66 illustrated in FIG. 3 is the same as thecontrol circuit of FIG. 2, except for the regulating circuit 68 toprovide a more uniform output frequency across the electrodes 16 and 18.Thus, the similar components have again been given similar referencecharacters in FIG. 3.

.The regulating circuit 68, as shown in FIG. 3, includes an additionalresistor 70 in the voltage divider circuit between the terminals 12 and14 and between the resistors 38 and 40 which are connected thereto andthe additional secondary portion 72 in the transformer 36, the diode 74and the Zener diode 76. In addition, the secondary transformer portion44 is separate from the primary portion 42 of the transformer 36.

With the regulating'circuit 68 connected as shown in FIG. 3, the initialvoltage applied to the oscillator transistor 26 is controlled by theZener diode 76 maintaining a substantially constant voltage across theresistors 70 and 40. If, in the operation of the oscillator 26, thecurrent through the primary portion 42 of the transformer 36 increasesbeyond a predetermined limit, the electrical signal developed in thesecondary portion 72 of the transformer 36 will provide a currentthrough the diode 74, Zener diode 76 and resistance 40 and thetransformer secondary portion 34 in opposition to the current flowproduced due to the source of electrical energy across the terminals 12and 14 through the resistors 38, 70 and 40 to reduce the bias on thetransistor 26 whereby the current flow is reduced to within thepredetermined limits therefor.

Thus, it will be seen that with the regulating circuit 68 in the controlcircuit 66 of FIG. 3 a substantially constant signal is fed to thecapacitor during each oscillation of the oscillator 26, whereby thecharge is built up on capacitor 22 in a uniform manner and the frequencyof discharge of the capacitor 22 is thus maintained substantiallyconstant even though 'the input voltage across the terminals 12 and 14may vary considerably.

' The embodiment 78 of the control circuit of the invention illustratedin FIG. 4 includes the oscillator circuit 80, a storage capacitor 82 anda trigger circuit 84 through which the capacitor 82 is discharged. Thecircuit 86 of the control circuit 78 is provided to maintain apredetermined charge on the capacitor 82 indicated by the light 88. Thecircuit 90 prevents operation of the oscillator circuit 80 duringdischarge of the capacitor 82 through the trigger circuit 84.

The oscillator circuit, 80 again includes the oscillator transistor 92,transformer 94 having the primary winding 96 and the secondary windings98 and 100, and the voltage divider including resistors 102 and I04.Operation of the oscillator circuit 80 is as considered in conjunctionwith control circuit 10. The capacitor 82 is again charged through arectifying diode 106.

The circuit 86'for maintaining a predetermined charge on the capacitor82 includes the transistor 108 connected to conduct in response to abias applied thereto on'current flow through the resistor 110. Currentflows through the resistor 110 on conduction of the Zener diode 112 inseries with the resistor 1 l0 and resistor 114 across the capacitor 82.Resistors 110 and 114 are not essential. Circuit 86 further includes thelight 88, capacitor 116 and Zener diode 118 connected as shown in FIG.4.

In operation a voltage is applied across terminals and 132, as before,to provide a bias for the oscillator transistor 92 across the resistor104 of the voltage divider to cause the oscillator 92 to conduct throughthe transformer primary portion 96. Conduction of the oscillatortransistor 92 will cause the transistor 92 to be cut off due to thesignal in transformer secondary portion 100 and produce a signal in thesecondary portion 98 of the transformer 94, whereby a signal is passedthrough the diode 106 to the capacitor 82 where it is stored as before.

The signal built up on the capacitor 82 over several cycles of theoscillator 92 will eventually reach a predetermined value which it isdesired to maintain on the capacitor 82. At the upper limit of thedesired voltage on the capacitor 82, say, for example, 120 volts, theZener diode 112 will conduct to provide a forward bias on the transistorI08, whereby the transistor 108 conducts to start a discharge of thecapacitor 82 and build up a voltage on the capacitor 116 as well aslight the light 88 indicating the desired voltage on the capacitor 82.

At a predetermined level of charging of the capacitor 116,

the Zener diode 118 will be caused to conduct so that the transistor 92will be cut off preventing additional chargingof the capacitor 82.Whenthe charge has dissipated from the capacitor 82 to a lower limit ofthe desired voltage, which may, for example, be maintained withinone-tenth of a percent of a desired voltage, it will render the Zenerdiode I12 nonconductive to remove, the bias from the transistor 108whereby the capacitor 116 will discharge slightly and the Zener diode118 reestablishes to again permit oscillation of the oscillator 92 andrebuilding of the charge on the capacitor 82. The charge on thecapacitor 116 may, for example, vary between 24 and 22 volts with a 36volt input.

The above indicated operation will continue indefinitely to maintain thevoltage on the capacitor 82 within the desired limits until the triggerswitch 120 in the trigger circuit 84 is closed whereby a pulse ofelectrical energy is passed through the primary portion 134 of thetransformer 124 to the secondary portion 136 thereof. A trigger pulse isthus provided on the trigger electrode of the silicon control rectifier126 to cause the rectifier 126 to conduct and provide a discharge pathfor the capacitor 82 through the solenoid 128 or other load structuresuch as an ordinary electric dynamite cap. The solenoid 128 may beconnected to fire a missile such as a grenade, or perform otherfunctions as desired.

The circuit 90 which includes the capacitor 138, resistor and resistor142 in series therewith and the transistor I44 connected as shown inFIG. 4, will cause the oscillator92 to cease oscillating during thedischarge of the capacitor 82 and for a period thereafter sufficient forthe silicon controlled rectifier 126 to fully turn off whereby thetrigger 120 must be closed to provide each actuating impulse through theload 128.

Thus, in operation, the capacitor 138 will charge in the polarity shownduring charging of the capacitor 82 to maintain the transistor 144 in anoff condition. When the capacitor 82 discharges the left side of thecapacitor 138 goes from approximately 120 volts positive to zero, forexample, to provide a bias on the transistor M4 turning the transistor144 on. With the transistor 144 turned on the base of transistor 92 willbe substantially grounded to maintain the oscillator 80 in an off.condition until the charge on the capacitor 138 is dissipatedsufficiently to lower the bias on transistor 144 to the nonconductinglevel again.

The embodiment of the invention illustrated in FIGS. 5 and 6 is capableof receiving a direct or alternating current input signal over a widerange of supply voltage and providing a regulated output signal over awide range of loads which output signal may be converted fromalternating to direct current inverted in polarity and may higher orlower in signal strength than the input signal. Further, the transfer ofthe signal from the oscillator portion of circuit 150 to the storageportion of the circuit will be at a theoretical 100 percent efficiency.

The circuit 150 includes the oscillator circuit 152, the storage circuit154, the regulating and feedback circuit 156 and the buffer circuit 158.The input which may be a direct current signal or an alternating currentsignal having a wide range of voltage is applied to the terminals 160and 162 while the output signal will be taken across the terminals 164and 166.

The oscillator circuit 152 is entirely similar to the oscillator circuit20 in both construction and function and will not therefore beconsidered in detail, except to point out that the separation of theprimary portion 168 and the secondary portion 170 of the transformer 172will not affect the function of the oscillator.

The storage circuit 154 is again similar to that of the modification 10of the invention and includes the storage capacitor 174 and the diode176. With the diode 176 in the circuit in one direction, as shown inFIG. 5, the signal stored on the capacitor 174 due to the signal fromthe oscillator circuit 152 will have a positive polarity. With the diode176 turned in the opposite direction, as shown in FIG. 6, the signal onthe capacitor 174 will be inverted in polarity so as to be negative atterminal 164, as shown in FIG. 6.

The output from the capacitor 174 is continuous and is regulated by theZener diode 178 positioned with the proper polarity in accordance withthe polarity of the signal at the terminal 164, as shown in FIGS. 5 and6. The signal across the Zener diode 178 is further used as a feedbacksignal through the circuit 156 and across the resistor 180, as shown inFIG. 5, to control the signal input to the oscillator 152.

To isolate the control of the oscillator from the effects of the load onthe feedback signal through the Zener diode 178 the buffer circuit 158is provided. It will be understood that the feedback signal from theZener diode 178 may be connected to regulate the oscillator circuit in anumber of different positions, as shown for example in FIG. 6, whereconductor end X may be connected at X., X or X The buffer circuit 158 isof course not necessary.

Thus in overall operation of the embodiment 150 of the invention, aninput signal is provided across the terminals 160 and 162 which may beeither an alternating or direct current signal to produce a pulsatingsignal through the transformer primary winding 168 as before to induce apulsating signal in the transformer secondary winding 170 on collapse ofthe field in the transformer primary winding 168. The signals from thetransformer secondary winding 170 are passed through the diode 176 andstored on the capacitor 174. The signal on the capacitor 174 is drainedfrom the capacitor 174 through the terminal 164 and is maintained at asubstantially constant voltage by the Zener diode 178 in conjunctionwith the input signal to the capacitor 174. The signal through the Zenerdiode 178 is fed back to the oscillator circuit 152 to regulate theinput signal thereto in accordance with the signal on the capacitor 174.As indicated above, the feedback signal may be passed through the bufferamplifier circuit 158 to isolate the oscillator from the effect of, forexample a changing load.

While three embodiments of the present invention and modificationsthereof have been considered in detail, it will be understood that otherembodiments and modifications are contemplated by the inventor.

What I claim as my invention is:

1. A circuit for providing a controlled pulse of electrical energycomprising a source of electrical oscillations, electrical storagemeans, electrical reactance means for transferring electrical energyfrom the source of electrical oscillations into the storage means toprovide an electrical signal therein, means connected between thestorage means and source of electrical oscillations for maintaining thevoltage of the electric signal in the storage means betweenpredetermined limits comprising a semiconductor device includingemitter, collector and base electrodes, a capacitor connected in serieswith the emitter and collector electrodes of the semiconductor deviceacross the electrical storage means, resistance means and a voltageregulating device connected in series across the electrical storagemeans, said base of said semiconductor device being connected betweenthe resistance means and voltage regulating device and a voltageregulating device connected at one end between the capacitor and thecollector of the semiconductor device and connected at the other end tothe source of electrical oscillations, and means for providing acontrolled discharge of the electrical signal in the storage meansacross a load.

2. Structure as set forth in claim 1 and further including an indicatorconnected across the capacitor.

3. Structure as set forth in claim 1 wherein the means for providing acontrolled discharge of the electrical signal in the storage meansacross a load comprises a silicon controlled rectifier having primaryelectrodes connected across the storage means and a control electrode, atransformer secondary winding connected between one of the primaryelectrodes and the control electrode of the silicon controlled rectifierand a switch and transformer primary winding connected across thecapacitor and operably associated with the transformer secondarywinding.

4. Structure as set forth in claim 1 and further including means forturning off the source of electrical oscillations during discharge ofthe storage means comprising a second semiconductor device havingemitter, collector and base electrodes, the emitter and collectorelectrodes of which are connected in series to the source of electricaloscillations and a capacitor and voltage divider resistance connected inseries with each other and across the storage means with the base of thesecond semiconductor device connected to a point on the voltage dividerresistance.

5. A circuit for providing a controlled pulse of electrical energycomprising a source of electrical oscillations including a firsttransistor having emitter, base and collector electrodes, a primarytransformer winding connected in series with the emitter and collectorof the first transistor across a direct current power supply, a voltagedivider resistor connected across the source of electrical energy andfeedback coil connected to a point on the voltage divider resistor andto the base of the first transistor operably associated with thetransformer primary winding, electrical storage means comprising acapacitor, electrical reactance means for transferring electrical energyfrom the source of electrical oscillations into the storage means toprovide an electrical signal therein including a transformer secondarywinding operably associated with the transformer primary winding and adiode in series with each other connected across the electrical storagemeans, means connected between the electrical storage means and thesource of electrical oscillations for maintaining the voltage of theelectric signal in the electrical storage means between predeterminedlimits comprising a second transistor having emitter, base and collectorelectrodes, a second capacitor connected in series with the emitter andcollector of the second transistor across the electrical storage means,a resistor and Zener diode connected in series across the electricalstorage means, the base of the second transistor being connected betweenthe resistor and Zener diode and a second Zener diode connected betweenthe capacitor and second transistor on one side and between thecapacitor and second transistor on one side and between the voltagedivider resistor and feedback winding of the source of electricaloscillations on the other side, means for indicating a voltage betweenthe predetermined limits on the electrical storage means comprising alight connected across the second capacitor, means for providing acontrolled discharge of the electrical signal in the electrical storagemeans across a load comprising s switch and second primary transformerwinding connected across the second capacitor, a silicon controlledrectifier having two primary electrodes and a control electrode, theprimary electrodes of which are connected in series with the load acrossthe storage means, and a second secondary transformer winding operablyassociated with the second primary transformer winding connected betweenone of the primary electrodes and the control electrode of the siliconcontrolled rectifier.

6. Structure as set forth in claim 5 and further including means forturning off the source of electrical oscillations during discharge ofthe electrical storage means comprising a third transistor havingemitter, base and collector electrodes, the emitter and collectorelectrodes of which are connected in series across the feedback windingand the emitter base circuit of the first transistor and a capacitor andsecond voltage divider resistor connected in series across the thestorage means, the base of the third transistor being connected to apoint on the second voltage divider resistor.

1. A circuit for providing a controlled pulse of electrical energycomprising a source of electrical oscillations, electrical storagemeans, electrical reactance means for transferring electrical energyfrom the source of electrical oscillations into the storage means toprovide an electrical signal therein, means connected between thestorage means and source of electrical oscillations for maintaining thevoltage of the electric signal in the storage means betweenpredetermined limits comprising a semiconductor device includingemitter, collector and base electrodes, a capacitor connected in serieswith the emitter and collector electrodes of the semiconductor deviceacross the electrical storage means, resistance means and a voltageregulating device connected in series across the electrical storagemeans, said base of said semiconductor device being connected betweenthe resistance means and voltage regulating device and a voltageregulating device connected at one end between the capacitor and thecollector of the semiconductor device and connected at the other end tothe source of electrical oscillations, and means for providing acontrolled discharge of the electrical signal in the storage meansacross a load.
 2. Structure as set forth in claim 1 and furtherincluding an indicator connected across the capacitor.
 3. Structure asset forth in claim 1 wherein the means for providing a controlleddischarge of the electrical signal in the storage means across a loadcomprises a silIcon controlled rectifier having primary electrodesconnected across the storage means and a control electrode, atransformer secondary winding connected between one of the primaryelectrodes and the control electrode of the silicon controlled rectifierand a switch and transformer primary winding connected across thecapacitor and operably associated with the transformer secondarywinding.
 4. Structure as set forth in claim 1 and further includingmeans for turning off the source of electrical oscillations duringdischarge of the storage means comprising a second semiconductor devicehaving emitter, collector and base electrodes, the emitter and collectorelectrodes of which are connected in series to the source of electricaloscillations and a capacitor and voltage divider resistance connected inseries with each other and across the storage means with the base of thesecond semiconductor device connected to a point on the voltage dividerresistance.
 5. A circuit for providing a controlled pulse of electricalenergy comprising a source of electrical oscillations including a firsttransistor having emitter, base and collector electrodes, a primarytransformer winding connected in series with the emitter and collectorof the first transistor across a direct current power supply, a voltagedivider resistor connected across the source of electrical energy andfeedback coil connected to a point on the voltage divider resistor andto the base of the first transistor operably associated with thetransformer primary winding, electrical storage means comprising acapacitor, electrical reactance means for transferring electrical energyfrom the source of electrical oscillations into the storage means toprovide an electrical signal therein including a transformer secondarywinding operably associated with the transformer primary winding and adiode in series with each other connected across the electrical storagemeans, means connected between the electrical storage means and thesource of electrical oscillations for maintaining the voltage of theelectric signal in the electrical storage means between predeterminedlimits comprising a second transistor having emitter, base and collectorelectrodes, a second capacitor connected in series with the emitter andcollector of the second transistor across the electrical storage means,a resistor and Zener diode connected in series across the electricalstorage means, the base of the second transistor being connected betweenthe resistor and Zener diode and a second Zener diode connected betweenthe capacitor and second transistor on one side and between thecapacitor and second transistor on one side and between the voltagedivider resistor and feedback winding of the source of electricaloscillations on the other side, means for indicating a voltage betweenthe predetermined limits on the electrical storage means comprising alight connected across the second capacitor, means for providing acontrolled discharge of the electrical signal in the electrical storagemeans across a load comprising s switch and second primary transformerwinding connected across the second capacitor, a silicon controlledrectifier having two primary electrodes and a control electrode, theprimary electrodes of which are connected in series with the load acrossthe storage means, and a second secondary transformer winding operablyassociated with the second primary transformer winding connected betweenone of the primary electrodes and the control electrode of the siliconcontrolled rectifier.
 6. Structure as set forth in claim 5 and furtherincluding means for turning off the source of electrical oscillationsduring discharge of the electrical storage means comprising a thirdtransistor having emitter, base and collector electrodes, the emitterand collector electrodes of which are connected in series across thefeedback winding and the emitter base circuit of the first transistorand a capacitor and second voltage divider resistor connected in Seriesacross the the storage means, the base of the third transistor beingconnected to a point on the second voltage divider resistor.